The objectives of the research program are (1) to elucidate the relationship between physiochemical properties and chemical structures of the drugs, and (2) also to understand the exact molecular mechanism by which these drugs inhibit nucleic acid and protein synthesis. The drugs chosen for studies are bleomycins, phleomycins, chromomycin, olivomycin, mithramycin, anthracyclines, anthramycin, sideromycin, mitomycin C, psoralen, rifamycins, miracil D, chlorquine, edeines, netropsin, distamycin, ostreogrycin B, gougerotin and vancomycin. Also complexes of these drugs with fragments of nucleic acids and proteins will be investigated. The methods used for investigations will be mainly X-ray crystallography and some times other spectral methods. The results of above investigations will help reveal the sites of interaction of these drugs to the target molecules and thus models can be postulated. Also modifications to the structures of the drugs can be postulated to enhance their therapeutic selectivity.